The present invention relates to an underwater explosive device and, more particularly, to a new and improved explosive device for underwater applications which is constructed to increase the extent of reaction, the pressure, temperature and bubble energy.
Underwater explosions rely on two different characteristics for damage mechanismsxe2x80x94shock and bubble. The shock parameter is driven by the detonation pressure of the explosivexe2x80x94which can be estimated from the plate dent test (although products density complicates this measurement). The shockwave shatters targets that are relatively close to the detonation. The bubble parameter, however, can be most damaging, especially to a surface target such as a destroyer. As the bubble rises, it alternately overexpands and then contracts in the water, sending out a pressure pulse on each oscillation. The greater amount of gas in the bubble and the hotter the product gases contained therein, the more effective it is for damaging a target.
For metallized explosives to achieve the hottest product gases at the highest temperature, and to give the biggest bubble requires that oxidation be complete and to be completed in a time period that matches the kinetics of the reactions. Expansion of the bubble lowers the pressure and temperature and slows (and then kinetically freezes) the reactions. Any process that requires significant mixing time will be detrimental to achieving maximum reaction output. Thus, although water can be an acceptable oxidizer for the fuel-rich products of detonation, there is a significant penalty because of the difficulty in mixing gaseous reaction products with the liquid water as the bubble expands. The water is pushed back instead of mixing with the hot gases. Even adding solid oxidizer particles to the explosive formulation does not give optimum results.
Accordingly, a need has arisen for an underwater explosive device which is not subject to the disadvantages of existing underwater explosives and possesses increased performance with respect to shock and bubble characteristics. The underwater explosive device of the present invention meets this need.
The underwater explosive device of the present invention comprises a suitable explosive for underwater use surrounded by oxygen gas under high pressure. This construction is advantageous for a number of reasons. First, the oxygen gas is not in and of itself a hazardous material. While it supports combustion, it is not combustible. Second, tank technology is available to house oxygen gas at high pressures such as 4350 psia. Third, and most importantly, the addition of high pressure oxygen has the capability to magnify the explosive effects of an underwater explosive, such as a titanium, magnesium or aluminum-loaded explosive, allowing for a small charge to appear much bigger. The gas-gas reactions are quick enough to significantly enhance bubble gas volume and temperature of the explosive reaction.